Don't publish story text for "close" stories to Asana

Summary: Ref T2852. After some discussion, Asana doesn't want "close" stories either.

Test Plan: Used bin/feed republish to publish close and non-close stories from Differential and Diffusion. Verified comments were synchronized in the expected cases.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2852

Differential Revision: https://secure.phabricator.com/D6697